Calling Contains on an empty array returns int, not bool

[tomp31]

Executing the following LINQ query does not work in EF Core 2.1.1 (where Countries is an arbitrary DbSet and CountryId is an arbitrary int property):

var ids = new List<int>();
await _context.Countries.Select(e => new GetCountryDto
{
    BoolVariable = ids.Contains(e.CountryId)
}).ToListAsync(cancellationToken);

Looking at the EF logs, I see the starts of an attempt to translate the query:

Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor
Optimized query model: 
'from Country e in DbSet<Country>
select new GetCountryDto{ BoolVariable = 
        (from int <generated>_1 in __ids_0
        select [<generated>_1]).Contains([e].CountryId) }
'

but the command eventually run is

Executed DbCommand (3ms) [Parameters=[], CommandType='Text', CommandTimeout='60']
SELECT 0 AS [BoolVariable]
FROM [General].[Countries] AS [e]

Because the 0 returned is an int and not a bool/bit, I get System.InvalidOperationException: An exception occurred while reading a database value. The expected type was 'System.Boolean' but the actual value was of type 'System.Int32'.

However, if I change the array on which Contains is called to not be empty:
var ids = new List<int> {1};
then the SQL generated is correct and includes CASTs:

Executed DbCommand (2ms) [Parameters=[], CommandType='Text', CommandTimeout='60']
SELECT CASE
    WHEN [e].[CountryId] IN (1)
    THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT)
END AS [BoolVariable]
FROM [General].[Countries] AS [e]

EF Core version: 2.1.1
Database Provider: Microsoft.EntityFrameworkCore.SqlServer
Operating system: Windows 10
IDE: Visual Studio 2017 15.5

[maumar]

possible dupe of #12280

[maumar]

I verified this is a dupe of #12280 - this issue will be fixed in the next patch (2.1.3)

[tomp31]

Thank you and sorry for not finding the duplicate issue.